Imprinting

Imprinting is a term used for two related but distinct phenomena in biology. In behavioral science, imprinting refers to rapid and durable learning that occurs during a restricted early-life window, known as a critical or sensitive period. During this time, young animals form strong associations and preferences, typically toward a caregiver or other salient object, which guides subsequent behavior. The best-known examples come from Konrad Lorenz's work with greylag geese, in which hatchlings followed the first moving object they observed, usually their mother. Filial imprinting describes the attachment to a caregiver, while sexual imprinting can influence later mate preference. Imprinting is usually irreversible after the sensitive period and depends on sensory input such as visual or auditory cues.

Genomic or genetic imprinting is a separate concept in which the expression of certain genes depends on whether the gene is inherited from the mother or the father. This parent-of-origin effect is achieved by epigenetic marks such as DNA methylation established in the germ line and maintained in tissues. Genomic imprinting regulates growth and development and is especially important in placental mammals. Disruptions of imprinting can cause disorders, including Prader-Willi syndrome and Angelman syndrome, depending on which parent's gene is affected. Imprinting across the genome is a major topic in genetics and developmental biology.